There are many situations in which it is desirable to apply a graphic to a surface and subsequently apply paint. In order for the graphic to be visible after paint is applied a removable protective layer must be applied to the outward facing surface of the graphic. This removable protective layer or premask, as it is known in the art, is removed from the graphic after the paint is applied to expose the graphic.
It is desirable to apply the graphic before the substrate is painted because, after painting and premask removal, the edges of the graphic are embedded under the paint. The graphic is thus much more difficult to remove or damage and is also more aesthetically pleasing. A premask graphic inserted under the paint is also useful to hide a paint break line. If a conventional graphic, for example a stripe, is applied over a paint break line, the break telegraphs through the stripe and is aesthetically displeasing.
A prevalent application for this type of graphic is in the automotive industry. Graphics of various configurations, including pin-stripes, designs, logos, trademarks, fine dot patterns, etc., are applied to automobile bodies. These graphics are typically applied to the automobile prior to the application of the final paint coat for the above reasons. The top coat of an automobile is typically baked at between 120.degree. C. to 150.degree. C. to harden the paint.
A significant problem with conventional premask tapes is that adhesion of the premask adhesive increases during this baking cycle, resulting in difficult removal of the premask from the graphic. If adhesion between the premask and the graphic exceeds the adhesion between the graphic and the automobile, the graphic will be removed or damaged in the process of removing the premask. This, of course, is clearly an undesirable result.
It is therefore desirable to provide a premask adhesive tape which adheres to the graphic during application to a surface, but which is detackified when subjected to the high temperatures of the paint bake cycle.